activation energy

• in a chemical reaction, a certain amount of energy needs to be suplied to the chemicals before the reaction will start - activation energy often provided as heat
• enzymes reduce the amount of activation energy needed for a reaction often making reactions happen at a lower temprature than without which speeds up the reaction rate
• when a substrate binds to an enzymes active site, an enzyme substrate complex is formed
• • its the formation of the enzyme-substrate complex that lowers the activation energy
  • if 2 substrate molecules need to be joined, attaching enzyme holds them closer so reduces any repulsion so the molecules can bond easily
  • if the enzyme is catalysing a breakdown reaction, fitting into active site puts a strain on bonds in the sbstrate. strain means substrate molecules break up more easily